Utility of ultrasound for body fat assessment: validity and reliability compared to a multi-compartment criterion

The importance of body composition for long term health and risk of chronic disease is expanding. It is widely recognized that high body fat is linked with a number of health disturbances, such as cardiovascular disease, metabolic abnormalities, hypertension, and sleep apnea, among others. Body composition assessment is an important aspect to be integrated within clinical practice as a preventative health approach. Specifically, patient care is shifting toward a more individualized preventative model with the establishment of patient-centered medical homes. Measurement of body composition can allow for treatment to be individualized to the patient, is predictive of disease risk, and allows for establishment of optimal nutrition and weight loss goals.

Portable ultrasound unit for measurements of body composition

Due to the potential use of body composition measurement in clinical settings, accurate and portable ‘field-based’ methods are needed. Ultrasonography (US), which has been around for decades, has contrasting support for its use as an accurate measurement technique for body composition. Technological advancements have transformed US to a portable, clear-resolution imaging package that is used in a variety of clinics for standard of care practice. Due to the equipment availability and widespread use of US in clinical environments, the ability to accurately assess body composition using US would be a potentially feasible option.

Our laboratory has developed a protocol to evaluate body composition using a standard B-mode clinical ultrasound. In this particular study we evaluated the accuracy and repeatability of using a portable B-mode ultrasound in comparison to a gold standard multi-compartment criterion for per cent body fat in overweight and obese adults.

Body fat was measured in fifty-one overweight and obese men and women to evaluate accuracy of the measurement. A subset of thirty-six individuals completed a second day of testing to obtain repeatability data. Based on the current results, US may over-predict %Fat in overweight/obese adults, but may still be a useful field-based measurement technique. The skill and time required for US measurement may be less than that required for skinfolds and other field based assessments and is more accurate than use of body mass index. Additionally, US may be more accurate than other commonly used field-based assessments. Values in the present study were more accurate for men, compared to women, which may be a function of the overall lower body fat in this sample of men. The US also proved to provide similar results from day one to day two, suggesting high repeatability.

How do these findings impact the public?

Ultrasound is one of few field based tools that can assess total and regional body composition. A number of new ultrasound devices are portable and compact, readily available, and widely used in clinical medicine. When comparing the overestimation of about 3.5%Fat, this is comparable to a number of other more widely accepted body composition techniques, including DEXA and BodPod, neither of which are portable. The repeatability of the US was high, providing potential use as a portable clinical tool. Using %Fat as a clinical outcome and/or tracking in the clinic, rather than body weight or BMI may be a better indicator of disease risk and progression. Future research should evaluate the feasibility of implementing such a tool within a clinic and as a component of a patient centered medical home.